The main objective of the study is to evaluate the effect on intestinal permeability of a supplementation with Lactibiane Tolérance® for 4 weeks (28 days) in patients suffering from irritable bowel syndrome (IBS) with diarrhea predominance.

Secondary objectives of the study are to evaluate the effects of supplementation with Lactibiane Tolérance® for 4 weeks (28 days) in patients suffering from IBS with diarrhea predominance on intestinal permeability, inflammation of the digestive tract, symptoms and comfort.

Single-center study in single open arms: 30 volunteer adults suffering from Irritable Bowel Syndrome (IBS) with diarrhea predominance and matching the criteria of inclusion and non-inclusion listed below.

single-center pilot study in single open arm:

• 2 to 6 weeks before enrollment: a screening visit (visit 0 [V0]) is carried out for verification of eligibility. time between V0 and V1 is a wash-out period with a duration decided by the physician (max 8 weeks).
• The experimental phase is composed of 2 visits (Visit 1 [V1] and Visit 2 [V2]) separated by 28 days (± 2 days) : from V1 to V2 patients are taking the product Lactibiane Tolérance®.
• V1 and V2 each include collection of stools, a blood sample, questionnaires on abdominal symptoms and quality of life, dynamic test of absorption of lactulose / mannitol to evaluate the intestinal permeability, recto-sigmoidoscopy with confocal endomicroscopy for in-vivo study of fluorescein leakage in the lamina propria and biopsies for ex-vivo measurements.
• "carmine red" test for the evaluation of intestinal transit speed is carried out the week before V1 and V2 (at least 72 hours before the visit). Questionnaires on abdominal symptoms as well as the frequency and consistency of stools are filled during the 7 days before V1 and V2 before.

Inclusion Criteria:

• Age from 18 to 75;
• With symptoms of IBS with predominant diarrhea according to the Rome III criteria;
• For women of childbearing age: effective contraception and agreement to keep it throughout the study;
• General and mental health compatible with participation in the study and to be followed as an outpatient in the opinion of the investigator: no clinically significant and relevant abnormality according to medical history and physical examination;
• Agreeing to maintain their lifestyle during the study (same eating habits and physical activity);
• Able and willing to participate in research in accordance with the protocol procedures particularly regarding consumption of the product under consideration and having signed an informed consent form dated;
• Belonging to a social security scheme;
• Willing to be included in the file of volunteers participating in biomedical research.

Exclusion Criteria:

• Having a history of hypersensitivity to any of the ingredients of the product under consideration;
• Having a history of hypersensitivity to fluorescein and / or red carmine (E120 food coloring);
• With immunodeficiency or with a severe or progressive disease (cardiac, pulmonary, hepatic, renal, hematologic, neoplastic, or infectious);
• With acute or severe chronic disease (chronic alcoholism, drug addiction) found incompatible with participation in the study by the investigator;
• Suffering from a metabolic disorder or a chronic inflammatory digestive disease affecting the intestinal transit or absorption of nutrients such as diabetes, hyperthyroidism, celiac disease or Crohn's disease;
• Having a medical history or current condition that, according to the investigator, may interfere with the results of the study or expose the subject to additional risk;
• Currently under medication or food supplement treatment, according to the investigator, may interfere with the results of the study or stopped within too short before inclusion in V1 (less than a month for antibiotics, pre and probiotics, less than 14 days for antidiarrheal, steroidal anti-inflammatories, NSAIDs, aspirin, antihistamines and drugs. treatment with maximum 2 concomitant psychotropic can be tolerated only if it exists for more than 3 months before inclusion);
• Having a lifestyle incompatible with the study by the investigator;
• Woman during pregnancy or breastfeeding or planning to become pregnant within 2 months;
• Planning to travel and hold during the study period or impossible to contact in case of emergency;
• Having a psychological or linguistic inability to understand and sign the informed consent;
• Participating in another clinical trial or exclusion period of a previous clinical trial;
• Having received over the past 12 months, no more than 4,500 euros in payment for participation in clinical trials;
• Under legal protection (guardianship, trusteeship) or deprived of his rights under the administrative or judicial decision.